1. a room in a building, ship, etc., that houses one or more steam boilers.
2. Slang. a. a place where illicit brokers engage in high-pressure selling, over the telephone, of securities of a highly speculative nature or of dubious value.
b. any room or business where salespeople, bill collectors, solicitors for charitable donations, etc., conduct an intensive telephone campaign, esp. in a fast-talking or intimidating manner.